Smelting and reduction of oxidic and sulphated lead material

Abstract

Processes are provided for the recovering of crude lead from materials containing lead substantially in the form of oxides and/or sulphates. The processes are carried out in a rotary converter with the rotation axis inclined to the plane of the vertical. In the process the materials containing lead are smelted and reduced while the furnace is rotated. Processes are also provided to separate and recover possible impurities of arsenic, antimony and tin.

We claim: 
     
       1. The method of recovering crude lead from materials containing lead substantially in the form of oxides and/or sulfates comprising charging said materials into a top blown rotary converter with an inclined rotational axis,   smelting said materials with the aid of a flame formed by burning fuel with oxygen over the surface of the bath of smelted material,   rotating the top blown rotary converter at 10-60 r p m and at a speed of 0.5 - 7 m/s measured at the inner periphery of the cylindrical part of the converter and with said rotational axis inclined to the horizontal plane so that the smelted material by means of the friction force induced by the rotational speed is lifted up along said inner periphery of the converter to a level at which smelt falls as finely-divided drops of liquid,   reducing oxides and/or sulfates of lead present in said smelted material during said rotation by introducing a reducing agent, and thereafter   tapping any slag formed and crude lead smelt from the converter.   
     
     
       2. The method according to claim 1, wherein said speed 2 - 5 m/s. 
     
     
       3. The method according to claim 1 in which a material containing lead obtained as intermediate products in the pyrometallurgical treatment of complex minerals contaning lead, zinc and/or copper is used. 
     
     
       4. The method according to claim 3, in which the material is obtained as dust from a lead smelting furnace. 
     
     
       5. The method according to claim 3, in which the material contains at least 20% by weight lead. 
     
     
       6. The method according to claim 1, in which said reducing agent is selected from the group consisting of carbon, metal sulphides, hydrogen, carbon monoxide and metallic iron. 
     
     
       7. The method according to claim 1, in which coal, oil, natural gas or pyrites are used as fuel. 
     
     
       8. The method according to claim 1, in which the reduction of the material is allowed to continue until the content of the lead oxide remaining in the slag is 5% by weight and that dust formed is returned to the converter. 
     
     
       9. The method according to claim 3, in which the reduction of the lead continues to a level less than 5% by weight lead oxide after which zinc compounds in the slag are reduced and vaporized and that the gas formed is separated in a gas purification system out of which materials containing zinc can be recovered. 
     
     
       10. The method according to claim 1, in which the material containing lead is accumulator scrap. 
     
     
       11. The method according to claim 1, in which the temperature during the smelting is maintained between 900° - 1250° C. 
     
     
       12. The method according to claim 1 wherein the top blown rotary converter is inclined 15° to 30° to the horizontal plane.